*{margin: 0; padding: 0;}
ul{
    list-style-type: none;
    border: 1px solid #ccc;
    width: 200px;
    margin: 100px auto;
    position: relative;
}
ul li{
    height: 45px;
    line-height: 45px;
    border-bottom: 1px dashed #ccc;
}
ul li a{
    text-decoration: none;
    color: #333;
    display: block;
    padding-left: 20px;
    background: url("../img/jiantouR.png") no-repeat 165px center;
}
ul li a:hover{
    background: #ccc url("../img/jiantouR.png") no-repeat 165px center;
    color: #fff;
}
ul li .list{
    width: 300px;
    height: 180px;
    border: 1px solid #000;
    position: absolute;
    left: 201px;
    top: -1px;
    display: none;
}